Method and device for recording and reproducing data

ABSTRACT

The actual data recording area on a recording medium is expanded by reducing a gap area between blocks of data for compensating for a delay time of data conversion while recording and reproducing data in a data recording and reproducing device. Based on a servo sector signal, a data sector generator circuit generates a write data sector signal indicating a timing of data recording in a data recording area, and outputs the write data sector signal to a delay circuit and a selector having two input ports and one output port. The delay circuit generates a read data sector signal by delaying the write data sector signal by a certain period, and outputs the read data sector signal to the selector. The selector outputs the write data sector signal when a write mode signal is active, and outputs the read data sector signal when the write mode signal is inactive.

TECHNICAL FIELD

This invention is related to data storage and retrieval device whichutilizes magnetic disk, magneto optical disk, optical disk, and magnetictape etc. Especially this invention is related to data storage andretrieval control method in which inter sector gap area is reduced whiledata recording and reproducing, and also related to device using it.

BACKGROUND ART

Data recording and reproducing method of conventional data storage andretrieval device is disclosed with an example of magnetic disk device.However the present invention is effective not only in magnetic diskdevice but also various data storage and retrieval devices in which atrain of data is separated to one or more blocks and recorded to thedata recording medium with arranging a gap before or after each sector,and data reproducing is performed through a reproducing head which facesand moves against said recording medium.

In a magnetic disk device, concentrically shaped recording area calledtrack is arranged on a magnetic disk namely the recording medium, anddata recording and reproducing is performed by the information on thetrack. Servo area is arranged intermittently and periodically on thistrack, and data area is also arranged between the servo area. Said datarecording area usually consists of plural of data sectors. Between thesectors, there are gap area which compensates the rotational speeddeviation or delay time of the operation of electronic circuit.Accordingly data cannot be recorded here.

Each sector consists of ID portion and data portion. ID portion consistsof synchronizing pattern to distinguish data while data reproducing, IDinformation to identify the data sector, and error check codes to detectthe ID information error. Data portion consists of synchronizing patternto distinguish data while data reproducing, data information, and errorcorrection code (ECC) etc.

Recording and reproducing circuit which performs recording andreproducing of data on said data portion consists of read circuit, writecircuit, and data control circuit. Read circuit handles reproducing ofsignal from ID portion and data portion. Write circuit handles recordingthe signal to data portion. Based on the servo sector signal of saidservo area, data control circuit generates data sector signal which isactivated at the start point of synchronizing pattern of ID portion, andcontrols overall recording and reproducing operation of the device.

A data recording procedure is as follows: ID data is reproduced withreference to the data sector signal as the origin, it is confirmed thatthe reproduced ID data identifies the correct sector to be recorded, andwrite data is recorded by the write circuit. A data reproducingprocedure is as follows: ID data is reproduced, it is confirmed that thereproduced ID data identifies the correct sector to be reproduced, thefollowing data area is read back by the read circuit, and the desireddata of the sector is obtained.

Further, detail procedure is described as follows. Read gate signal isactivated by the data control circuit at the appropriate timing duringthe synchronizing pattern area of the ID portion with referring to thedata sector signal as the origin. Read circuit synchronizes with thesignal recorded in ID portion, decodes the reproduced signal to data,gets the ID information, and transmits the ID data to data control part.Data control circuit verifies the error check code of ID information andtemporarily closes the read gate, then reactivates the read gate signalat an appropriate timing during the synchronizing pattern of the dataportion after ID portion. Read circuit synchronizes with data portion,decodes the reproduced signal, and transmits the reproduces data to datacontrol circuit. After decoding error correction code portion (ECC) ofdata portion, data control circuit closes the read gate, and shifts to astatus of waiting the data sector signal for decoding next ID portion.

In a series of data recording and reproducing operation, gap areas arearranged between data sectors, or before and after ID portion and dataportion, in order to compensate the deviation of recording positionwhich is caused from the rotational speed deviation of magnetic diskwhich is the recording medium in magnetic disk device, or the deviationof tape running speed in magnetic tape drive, and to compensate thedelay in data recording operation of write circuit, or the delay in datareproducing operation of read circuit.

In most cases, the rotation of magnetic disk is controlled based on aclock signal generated by a crystal oscillator, so that usually therotational speed is stable. However when the device is exposed to ashock or vibration, or when seek operation occurs, the rotational speedof the disk varies because of the deviation of the power voltage ormechanical resonance from seek operation. In such cases the amount ofthe deviation of the rotational speed is about 0.1%. Above mentioned gapareas were necessary to avoid the data destruction from the deviation ofthe rotational speed.

Delay time in operation of write or read circuit varies according to thedata conversion method (coding format ) or the reproducing method ofreproducing the data recorded on the data storage medium (here magneticdisk). As for the coding method, recently more efficient block codingmethod such as 8 to 9 coding method or 16 to 17 coding method isgenerally used instead of formerly used 2 to 7 RLL or 1 to 7 RLL. As forthe reproducing method, PRML method (Partial ResponseMaximum-Likelihood) or EPRML (Extended Partial ResponseMaximum-Likelihood) is generally used in order to obtain the bettersignal to noise ratio. With the increasing complexity of the dataconversion method or signal reproducing method, coding or decoding timeincreases, accordingly the operation time (delay time in data recordingor reproducing) required the reproduced data to reach to data controlcircuit from read circuit increases. Now data control circuit cannotstart the operation of next data portion or ID portion until ECCdecoding operation of the reproduced data finishes. So gap area to waitthe delay time of write or read circuit was necessary before and afterthe data portion or ID portion.

Track format in the conventional magnetic disk device is shown in FIG.7. Recording and reproducing operation of data is performed depending onone data sector signal (for write and read) as timing signal. Servo areaand SYNC pattern, those are necessary to record and reproduce data ondata area, data recording area, gap area to compensate rotational speeddeviation, and gap area to compensate the operation time (dataconversion delay time) of write or read circuit are intermixedlyarranged on the track. And there are time delay each between write datato be recorded on the recording medium, actually recorded data on themedium, and reproduced data respectively.

A method to delay the output of index signal and sector signal exceptformatting in order to avoid write splicing is disclosed in unexaminedpatent publication 5-303836 Japan. However only the timing of generatingthe sector signal is changed between formatting and not formatting, butthere is no effect to reduce above mentioned gap area (namely the areacannot be used to store data).

In a magnetic disk device by the prior technology, starting of write orread operation of data is triggered by the data sector signal generatedfrom servo signal. The data sector signal was generated at the sametiming for both writing and reading data. In such above mentioned priorcontrol method of data recording and reproducing, said gap area isdetermined by the total of the deviation of relative speed (rotational)of the medium, the delay in write operation, and the delay in readoperation. Originally the gap area cannot be used for data recording.Accordingly by increasing the gap area, the actual data recording areadecreases.

DISCLOSURE OF THE INVENTION

The purpose of the present invention is to eliminate the portion of gaparea which is useless to store the data, so that to increase thesubstantial data recording area of the recording medium. Another purposeof the present invention is to reduce the portion of gap area with whichthe delay time of read or write operation is compensated, so that theefficiency of the data recording is improved.

In the data recording and reproducing method by the present invention,to achieve the above mentioned object, data sector signal generatingmeans is provided where the timing of generating the data sector signalof data recording and reproducing is different. Here data sector signalis generated for each sector. Said data sector signal generating methodcan issue the two kinds of data sector signal either by changing thetiming from one source signal or from pre-arranged two source signal ofthe different timing.

Further, in order to reduce the gap portion which compensates the delaytime of read operation, it is provided with data sector generating meanswhich generates data sector signal to start the data reading of the nextsector before completing the data output operation of the currentsector, and data reproducing means.

Or, it may be provided with data sector generating means which startssynchronizing with sync pattern and reproducing, before completing thedata output operation of the current sector, and data reproducing means.

In order to reduce the gap portion which compensates the delay time ofwrite operation, it is provided with data sector generating means whichgenerates data sector signal to start the data writing for the nextsector before completing the data output of current sector.Consequently, the gap area is substantially eliminated, and the datarecording efficiency on the recording medium can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a magnetic disk device by the presentinvention.

FIG. 2 is a block diagram which shows a configuration of data sectorgenerator 6 in FIG. 1.

FIG. 3 is a block diagram which shows a configuration of the readcircuit 3 in FIG. 1.

FIG. 4 is a block diagram which shows a configuration of the writecircuit 4 in FIG. 1.

FIG. 5 shows the timing of reading and writing in the present invention.

FIG. 6 shows the timing of the read operation by the present invention.

FIG. 7 shows the timing of reading and writing in the prior technology.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a block diagram of a magnetic disk device which is anembodiment of the present invention. Reproducing and recording operationis disclosed.

Data reproducing operation is as follows. Data and servo informationstored in the data disk 1 is read back as analog read signal 8 (headplay back signal 8) and is inputted to read circuit 3 and servo sectorgenerator 5.

Based on the servo information in read back signal 8, Servo sectorgenerator 5 outputs servo sector signal 10 which shows start point ofservo information recording area to data sector generator 6. Followingservo sector signal 10, data sector generator 6 outputs data sectorsignal 15 (digital signal) which indicates the base timing for recordingand reproducing to and from the data recording area. Data sector signal15 is inputted to data control circuit 7, and based on data sectorsignal 15, data control circuit 7 outputs read gate 11 which is adigital signal and determines the area to import the data. While readgate 11 is active, read circuit 3 decodes reproduced signal 8 and outputto data control circuit 7 as read data 12.

Here, trigger signal 10 which indicates the origin of any recording areacan be issued by trigger signal generator 5 (not shown) to datagenerator 6 (not shown), and origin trigger signal 15 can be issued todata control circuit 7.

Then, the procedure of data recording operation is disclosed. Datarecording procedure performed based on data sector signal 15 likereproducing procedure. Above mentioned and not shown origin triggersignal 15 can also be used.

Data control circuit 7 issues write gate 13 which is digital anddetermines the data recording area based on the data sector signal 15which is issued from data sector generator 6. Further, data controlcircuit 7 outputs write data 14 to write circuit 4 while write gate 13is active. Write circuit 4 receives write gate 13 and write data 14,encodes write data 14, and records analog converted write data 9 to datadisk 1 through magnetic head.

Data sector generator 6 in the functional block diagram FIG. 1 isfurther described referring to FIG. 2.

Data sector generator 16 generates write data sector signal 19 based onthe input of servo sector signal 10. Write data sector signal 19indicates the timing of recording the data to data recording area on themedium.

Write data sector signal 19 is transmitted to delay circuit 17 andselector 18 which has 2 input port and 1 output port. Delay circuit 17outputs read data sector signal 20 which is a certain period delayedsignal of write data sector signal 19. These two signals are inputted toselector 18. Selector 18 outputs write data sector signal 19 as datasector signal 15 when write mode signal 21 is active, and outputs readdata sector signal 20 as data sector signal 15 when write mode signal 14is inactive.

Further, the circuit configuration is not limited as above. That means,only generating each signal as shown in FIG. 5 is necessary. One way isto provide the data control circuit with above mentioned function, andto transmit the write data sector signal in whether delayed of certainperiod or write data sector signal 19 itself depending on the existenceor no-existence of write mode signal 21, in either synchronously or asynchronously with a clock which is generated separately. Another way isto provide an additional control circuit to perform the same function.

Here, timing of the procedure of write and read operation is shown inFIG. 5.

When a magnetic disk device performs write operation, write mode signal21 (FIG. 2) is active and data sector signal 15 indicates the timingsignal to write data sector signal 19. Data control circuit 7 outputswrite gate 13 and write data 14 based on data sector signal 15 (writedata sector signal 19), and the information is written on to the datadisk 1. Because of the operation delay of write circuit 4, recordingposition lag occurs on data disk 1. Accordingly the write data sectorsignal 19 is asserted earlier with the delay time of write circuit 4.The following write data sector signal 19 is re-asserted aftertransmitting the write data and passing the gap period to compensate thedeviation of rotation. According to these means, the gap area includesonly the portion to compensate the deviation of rotation, and no portionfor the delay of prior write operation is included in the gap area.

On the other hand when a magnetic disk performs read operation, writemode signal 21 is inactive, and data sector signal 15 is the timingsignal indicated to read data sector signal 20. Read data sector signal20 is asserted at delayed timing with write data sector signal 19, andis generated at the start position of data recording area of the medium(FIG. 5). Read data 12 is transmitted to data control circuit 7 afterthe delayed operation of read circuit 3.

In case delay time of read operation is less than the time of gap areato compensate the rotational deviation, namely less than the time forthe magnetic head passes said gap area, the delay time of read operationis covered up. Consequently the gap area is not required to include thedelay time of read operation, so that the gap area can be reducedcompared to the prior technology.

Further the operation time after the issue of read command until theactual start of read operation of the data on the medium, or operationtime to store the data can be compensated similarly. To be more detail,the gap area on the medium can be eliminated by anticipation control ofthe data control circuit with reflecting the time after starting theinput of reproduced signal 8 to read circuit 3 and servo sectorgenerator 5 until it is converted to the information which the datacontrol circuit can distinguish, or the time after starting the transmitof the write data 14 to write circuit 4 until the starting of recordingthe magnetic field change which corresponds to the write analogue signalto the recording medium.

With another method than data sector generation circuit 16 of thepresent embodiment, it is possible to achieve the similar object. Forexample, similar function can be obtained by providing two kind ofcircuit in data sector generation circuit 16, that is write data sectorgeneration circuit and read data sector generation circuit, write datasector signal and read data sector signal are generated, and outputtingone of the two signals as the data sector signal. The only required isthat the timing between each signal is as shown in FIG. 5.

Then, when the read operation delay time is larger than the time whichthe magnetic head passes the corresponding gap area, an operationalcircuit is required as shown in FIG. 3. More detailed configuration ofread circuit 3 and data control circuit 7 in FIG. 1 is shown in FIG. 3.Read circuit 3 consists of analog decoder 22, read data synchronouscontrol circuit 23 and data conversion circuit 24.

Operational timing is shown in FIG. 6.

During read operation, based on data sector signal 15, data controlcircuit 7 generates sync control start signal 25 from either the fall ofwrite sector signal or the rise of read delay selector signal, and alsogenerates read gate 11 with the delayed timing of the rise of writesector signal. Sync control start signal 25 (FIG. 3) is transmitted toanalog decoder circuit 22 and read sync control circuit 23. Read gate 11is transmitted to data conversion circuit 24. When sync control startsignal 25 is activated, reproduced analog signal 8 is decoded throughanalog decoder circuit 22.

Decoded data is inputted to data conversion circuit 24 and read datasync control circuit 23. Read data sync control circuit 23 performsphase synchronizing of data with the sync pattern of reproduced signal8, and generates the reproducing clock signal. Decoded data is inputtedto data conversion circuit 24 with synchronizing the reproducing clocksignal, and the data code is converted and outputted to data controlcircuit 7 as read data 12.

Data control circuit 7 inactivates the sync control start signal 25(FIG. 6) when analog decoder circuit 22 finishes the processing ofreproduced signal 8, and inactivates read gate 11 when the output of allread data 12 is finished. After all, in case reproducing operation isperformed continuously, sync control start signal 25 is inactivated whenprocessing of all the data in one sector by analog decoder circuit iscompleted. Accordingly even though data transfer to data control circuit7 is not completed yet, by starting to wait the next sync control startsignal at the timing of sync control start signal 25 is inactivated, thedata decoding and sync control can be started when sync control signal25 is activated by next data sector signal 15.

By employing the present invention, even if the delay time of the readoperation exceeds the time of the gap area, the gap area does notinclude a portion of the read operation, so that the purpose of theinvention is achieved.

Further, the circuit configuration is not limited as above. That means,only generating each signal as shown in FIG. 6 is necessary. One way isto provide the data control circuit with above mentioned function, andanother is to provide a separate control circuit to perform the samefunction.

Next, in FIG. 4 another embodiment of a circuit is disclosed where saidgap area caused from the delay of write circuit is reduced.

In FIG. 4, gate generation circuit 26 is provided to write circuit 4 ofFIG. 1. From write gate signal 13 (FIG. 5) which indicates theoutputting period of digital data 14, gate generation circuit 26generates write gate with reflecting the delay time of data codeconversion of write data 14. That is, though the write gate signal 13 isclosed at completion of the transmitting of the write data 14 from datacontrol circuit 7 to write circuit 4, gate generation circuit 26 keepswrite gate depending on write gate signal 13 until the completion of therecording to the recording medium (disk). Accordingly, write circuit 4can continue to transmit coded recording data 9 (analog signal) tomagnetic head.

In the present embodiment, it is described referring to magnetic diskdevice. However, gap area reduction can be obtained by similar functionnot only in magnetic disk devices but also in optical disk devices ormagnetic tape devices.

The method by the present invention can be applied to not only datarecording and reproducing devices but also the components which composesthe relevant devices such as LSIs of data recording and reproducingcircuits or control circuits. Further, similar function can also beachieved by micro CPU.

In the data recording and reproducing method by the present invention,timing compensation is introduced to relatively cancel the delay time inwrite and read operation, so that the gap portion to compensate thedelay time of data processing can be eliminated or reduced.Consequently, improvement of the efficiency or data recording, namelythe expansion of the substantial data recording area on the recordingmedium can be obtained.

What is claimed is:
 1. A data recording and reproducing devicecomprising: data recording means which records data divided into aplurality of blocks on a recording medium such that there is a gap areabefore or after each of the blocks; data reproducing means whichreproduces data from the recording medium with a reproducing head toobtain reproduced data; and decoding means which decodes the reproduceddata to obtain decoded data and outputs the decoded data; wherein a timerequired for the reproducing head to pass the gap area is shorter than atime required for the decoding means to decode the reproduced data;wherein the data recording means records data in one block based on awrite data sector signal corresponding to the block; wherein the datareproducing means reproduces data from one block based on a read datasector signal corresponding to the block; and wherein a timing of theread data sector signal relative to the block is different from a timingof the write data sector signal relative to the block.
 2. A datarecording and reproducing method comprising the steps of: recording datadivided into a plurality of blocks on a recording medium such that thereis a gap area before or after each of the blocks; reproducing data fromthe recording medium with a reproducing head to obtain reproduced data;decoding the reproduced data to obtain decoded data; and outputting thedecoded data; wherein a time required for the reproducing head to passthe gap area is shorter than a time difference between a start of thedecoding step and a start of the outputting step; wherein in therecording step, data is recorded in one block based on a write datasector signal corresponding to the block; wherein in the reproducingstep, data is reproduced from one block based on a read data sectorsignal corresponding to the block; and wherein a timing of the read datasector signal relative to the block is different from a timing of thewrite data sector signal relative to the block.
 3. A data recording andreproducing device comprising: data recording means which records datadivided into a plurality of blocks on a recording medium such that thereis a gap area before or after each of the blocks; data reproducing meanswhich reproduces data from the recording medium with a reproducing headto obtain reproduced data; and decoding means which decodes thereproduced data to obtain decoded data and outputs the decoded data;wherein the decoding means starts decoding reproduced data reproducedfrom a second block before the decoding means finishes outputtingdecoded data obtained by decoding reproduced data reproduced from afirst block; wherein the data recording means records data in one blockbased on a write data sector signal corresponding to the block; whereinthe data reproducing means reproduces data from one block based on aread data sector signal corresponding to the block; and wherein a timingof the read data sector signal relative to the block is different from atiming of the write data sector signal relative to the block.
 4. A datarecording and reproducing method comprising the steps of: recording datadivided into a plurality of blocks on a recording medium such that thereis a gap area before or after each of the blocks; reproducing data fromthe recording medium with a reproducing head to obtain reproduced data;starting decoding the reproduced data to obtain decoded data; startingoutputting the decoded data as the decoding of the reproduced dataprogresses; finishing decoding the reproduced data; and finishingoutputting the decoded data; wherein finishing outputting decoded dataobtained by decoding reproduced data reproduced from a first block isperformed after starting decoding reproduced data reproduced from asecond block; wherein in the recording step, data is recorded in oneblock based on a write data sector signal corresponding to the block;wherein in the reproducing step, data is reproduced from one block basedon a read data sector signal corresponding to the block; and wherein atiming of the read data sector signal relative to the block is differentfrom a timing of the write data sector signal relative to the block. 5.A data recording and reproducing device comprising: data recording meanswhich records data divided into a plurality of blocks on a recordingmedium after relevant data is conversion processed by a write circuitsuch that there is a gap area before or after each of the blocks; datareproducing means which reproduces data from the recording medium with areproducing head to obtain reproduced data; and decoding means whichdecodes the reproduced data to obtain decoded data and outputs thedecoded data; wherein during data recording, a timing of starting thewrite circuit is earlier than a timing of starting the decoding means;wherein the data recording means records data in one block based on awrite data sector signal corresponding to the block; wherein the datareproducing means reproduces data from one block based on a read datasector signal corresponding to the block; and wherein a timing of theread data sector signal relative to the block is different from a timingof the write data sector signal relative to the block.
 6. A datarecording and reproducing method comprising the steps of: recording datadivided into a plurality of blocks on a recording medium such that thereis a gap area before or after each of the blocks; reproducing data fromthe recording medium with a reproducing head to obtain reproduced data;starting decoding the reproduced data; and starting a write circuitwhich conversion processes decoded data during data recording; wherein atiming of starting decoding the reproduced data is later than a timingof starting the write circuit when recording or reproducing data of oneblock; wherein in the recording step, data is recorded in one blockbased on a write data sector signal corresponding to the block; whereinin the reproducing step, data is reproduced from one block based on aread data sector signal corresponding to the block; and wherein a timingof the read data sector signal relative to the block is different from atiming of the write data sector signal relative to the block.
 7. A datarecording and reproducing device comprising: data recording means whichrecords data divided into a plurality of blocks on a recording mediumafter relevant data is conversion processed by a write circuit such thatthere is a gap area before or after each of the blocks based on a writegate generated by a write gate generating circuit in response to a writegate signal; data reproducing means which reproduces data from therecording medium with a reproducing head to obtain reproduced data; anddecoding means which decodes the reproduced data to obtain decoded dataand outputs the decoded data; wherein during data recording, even whenthe write gate signal is terminated, the write gate generating circuitcontinues to generate the write gate so that data continues to berecorded on the recording medium based on the write gate until recordingof the data is completed; wherein the data recording means records datain one block based on a write data sector signal corresponding to theblock; wherein the data reproducing means reproduces data from one blockbased on a read data sector signal corresponding to the block; andwherein a timing of the read data sector signal relative to the block isdifferent from a timing of the write data sector signal relative to theblock.
 8. A data recording and reproducing method comprising the stepsof: recording data divided into a plurality of blocks on a recordingmedium such that there is a gap area before or after each of the blocks;reproducing data from the recording medium with a reproducing head toobtain reproduced data; and starting a write circuit which conversionprocesses relevant data for recording on the recording medium; whereinthe write circuit continues to operate until recording of conversionprocessed data for one block has been completed; wherein in therecording step, data is recorded in one block based on a write datasector signal corresponding to the block; wherein in the reproducingstep, data is reproduced from one block based on a read data sectorsignal corresponding to the block; and wherein a timing of the read datasector signal relative to the block is different from a timing of thewrite data sector signal relative to the block.